1st Edition BIOL 252 Lecture 8 Outline of Last Lecture I Equilibrium II Vision III Sensory Transduction in the Retina IV Generating Optic Nerve Signal V How we Have Different Sensitivities VI Color Vision VII Visual Projection Pathway Outline of Current Lecture I The Skin Its Structure and Function II The Epidermis III The Dermis IV Hypodermis V Skin Coloration Current Lecture I II The Skin Its Structure and Function a Biological harm i Keeps microbes and pathogens out b Chemical harm i Waterproofing helps us to retain water or absorbing too much c Physical harm i Abrasions d Other functions i Vitamin D synthesis ii Sensory reception 1 Pain heat movement pressure light touch iii Thermoregulation 1 Involves all 3 layers of the skin iv Communication 1 Facial muscles skin color changes The Epidermis a Epidermal cell types i Keratinocytes and stem cells make keratin ii Melanocytes These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute III 1 Protect against UV light causes DNA mutations iii Tactile cells 1 Sensory receptor for touch iv Dendritic cells 1 Fight off microbes and bacteria for the immune system 2 First line of defense for body after the skin so 2nd line of defense 3 Signals to the rest of the immune system b Keratinized stratified squamous epithelium i Desmosomes strong mechanical linkages ii Stratum basale bottom most level iii Stratum spinosum 1 Spiny because beginning to dehydrate iv Stratum granulosum 1 Beginning process of cells dying start to become functional 2 Become dehydrated lose organelles 3 By the time they come to stratum corneum cells DEAD v Stratum corneum 1 Cells dead continually exfoliate vi Poll Everywhere 1 What is cancer Uncontrolled cell division 2 Which cells are least likely to become a skin cancer a Stratum granulosum b Other three types have naturally dividing cells c Pathology Skin Disorders i Cancers of the epidermis ii 1 Basal Cell Carcinoma 1 Stratum basale 2 Most common 3 Least dangerous 4 Carcinoma epithelial cancer iii 2 Squamous cell carcinoma 1 Arises w in stratum spinosum 2 Metastasizes leave tissue of origin and can travel to other places to lymph nodes and can be lethal iv 3 Malignant melanoma 1 Most readily metastasizing 2 Rare but deadly 3 Metastasizes readily and is fatal a Can have it all over your body The Dermis a Superficial Papillary layer i Areolar connective tissue ii Forms papillae dense w nerve endings and capillaries b Deep reticular layer IV V i Dense irregular connective tissue ii Contains larger blood vessels iii Some adipocytes iv Comprises most of dermis v Leather reticular layer c Why do we have fingerprints i To grip Hypodermis a Last layer of the skin b Fat layer at the bottom c Structure primarily adipose rich in blood vessels nerves d Functions fat energy storage thermal insulation communication e Health reflected by amount of fat that you have Skin Coloration a Ingesting of silver nitrate antibacterial properties i Man turns blue b Which molecule does not contribute to the normal color of skin i Hemoglobin ranges from red to purplish blue highly oxygenated red purple blue deoxygenated 1 Abnormal colors in skin a Cyanosis poorly oxygenated hemoglobin b Pallor yellow green pale skin resulting from poor blood supply c Erythema any abnormal reddening of skin overheating stress burns rashes d Jaundice yellowing due to buildup of bilirubin e Hematoma bruise mass of clotted blood ii Melanin provides pigment from yellowish to brown to black part of stratum basale 1 Produced by melanocytes distributes on external face of keratinocytes breaks down more rapidly in lighter skin tones 2 Abnormal colors in skin a Albinism lack of melanin genetic 3 Lots of melanin where strong UV light is equator iii Keratin waterproofs skin gives abrasion resistance iv Carotene normal pigment found in plants yellowish orangish 1 Carotenemia carotene is normal in small amounts but may accumulate in stratum corneum